Ankylosing spondylitis is a type of arthritis of the spine. It causes swelling between your vertebrae, which are the disks that make up your spine, and in the joints between your spine and pelvis. Ankylosing spondylitis is an autoimmune disease. This means your immune system, which normally protects your body from infection, attacks your body's own tissues. The disease is more common and more severe in men. It often runs in families.
